Control means for a random access storage system



March1,1966 J.E.SCHNOOR ETAL 3,238,509

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CONTROL MEANS FOR A RANDOM ACCESS STORAGE SYSTEM Filed Dec. 8. 1961 17 Sheets-Sheet 1'7 3,238,509 CONTROL MEANS FOR A RANDM ACCESS STORAGE SYSTEM Joerg E. Schnoor, Rolling Hills, Richard G. Fisher, Torrance, and Arthur M. Angel, Rolling Hills, Calif., assignors to The National Cash Register Company,

Dayton, Ohio, a corporation of Maryland Filed Dec. 8, 1961, Ser. No. 162,626 60 Claims. (Cl. S40-172.5)

This invention relates generally to high capacity, rapidly accessible random access storage units, and to improved means and methods for coordinating the operation of such units with the operation of a high-speed electronic data processor. More particularly, the invention relates to irnproved means and methods for coordinating the operation of a high-speed electronic data processor with the operation of one or more random access storage devices of the type disclosed in the commonly assigned Icopending patent application Serial No. 12,032, tiled March 1, 1960.

The advantages to be derived from a high capacity, rapidly accessible random access storage device for use in a computer system are so numerous and well recognized as to require little elaboration. However, in spite of the acknowledged advantages to be gained from the use of such a random access storage device, progress towards the development of a practical device has been quite slow and the computer art has been forced to rely on sequentially accessible magnetic tape units for much of its large capacity storage. The relatively few high capacity random access storage devices which have been attempted leave much to be desired, chiey because they suffer from one or more of the following disadvantages: (1) relatively slow access time, (2) limited storage capacity, (3) high cost, (4) failure to provide rapid interchangeability of storage elements, as a result of which, it is necessary to provide sucient built-in storage capacity for the maximum amount of data which might be required to be stored, and (5) the unit is not easily coordinated with the operation of a high-speed electronic data processor and vice versa so as to permit full advantage to be taken of both the random access capability of the random access unit and the high-speed capability of the processor.

The ran-dom access storage device disclosed in the aforementioned copending patent application, Serial No. 12,032 represents the first real breakthrough in the development of a commercial high capacity, rapidly accessible random access storage device, and makes it possible to substantially overcome the previously listed disadvantages which have hampered other random access storage devices. Briey, in a typical embodiment of the random access storage device disclosed in the aforementioned copending application, a rapidly removable magazine is provided containing a plurality of magnetic data storage strips (for example, 256 strips), each of which has a different set of binary coded notches provided at one end thereof representing the strip number. The magazine is mounted in the random access storage device so that each of the plurality of strips therein is vertically suspended from a plurality of selection rods (for example, eight rods). The selection rods are constructed and arranged in conjunction with the shape of the coded notches so that, by proper selection of the rods, a selected strip may be released and caused to drop under the inuence of gravity until it engages a rotating capstan to which it is drawn by means of a vacuum. Once engaged, the strip is rapidly accelerated to the surface speed of the capstan and, while on the capstan, is caused to traverse a plurality of read and write heads, in intimate head contact therewith, so as to permit reading and/ or writing on the strip. Provision is made to permit the strip to recirculate one or States Patent O ICC more times on the capstan before being returned to the magazine from which it was dropped. This is accomplished by means of a return gate which in one position allows the strip to remain on the drum for recirculation, and in the other position peels the strip from the capstan and causes it to enter a guide means which leads back to the magazine. The return to the magazine is accomplished by allowing the centrifugal force of the strip, obtained as a result of rotation of the strip by the capstan, to provide the momentum which sends the card through the return gate, and upward through the guide means, until it arrives at a magazine loader mechanism. The loader mechanism acts to return the card to the magazine, after which the strip is once again available for selection. The sequence of strips on the selection rods is, of course, inconsequential since the selection of a strip is independent of its position in the magazine.

Continuing with the description of the random access storage device of the aforementioned copending patent application Serial No. 12,032, it will be understsood that a large number of bits of data or information can be stored on each of the above-described magnetic data-storage strips which, for example, may be three and one-fourth inches wide and fourteen inches in length. Such a strip may typically store in excess of fifty-eight million binary bits. And, since according to the invention of the aforementioned patent application, any desired one of the strips may be selected, released, dropped, operated on, and returned to the magazine, all within a small fraction of one second, it is evident that the invention provides a random access storage device which not only has a remarkably high storage capacity, but in addition, provides a very rapid access time which is very much faster than that required, for example, with apparatus utilizing long runs of magnetic tape as the storage medium. Also, besides providing high storage capacity and rapid access, the random access storage device of the aforementioned copending patent application has the further advantage that a magazine containing a set of stiips may be easily and quickly replaced by any other magazine, as a result of which, access to almost any possible amount of stored information is made possible. Still further, in addition to providing these highly desirable random access capabilities, this random access storage device is also capable of efficient sequential operation, competitive with a conventional tape unit, so as to permit considerable versatility in the choice of operating mode.

With the above brief description of the random access storage device of the aforementioned copending patent application Serial No. 12,032 in view, it may now be stated that the primary object of the present invention is to further extend the considerable step forward achieved by this novel random access device by the provision of improved means and methods for coordinating the operation of a high-speed electronic data processor with one or more of such random access storage devices, in a manner so that the data processor as well as the storage devices can operate at maximum eiciency with a high degree of system iexibility.

Another object of this invention is to provide means for operating a random access memory device of the type disclosed in the aforementioned copending patent application in a manner so that jamming or destruction of the magnetic data-storage strips is prevented, and so that errors and/ or malfunctioning of the unit, if they should occur, are brought to the attention of the processor an-d/ or programmer.

Still another object of the present invention is to provide means :and methods for operating one or more random access storage devices with a high-speed electronic data processor so that each random access memory device can operate independently of, or in synchronism with,

Y means in its openposition. gate will act to remove a strip from the capstan;

vthe data processor in a manner which permits the most expeditious operation of all units.

A still further object of this invention is to provide means and methods in accordance with any one or more of the preceding objects which provide operation in a manner so that the status of each random access device is made readily available to the data processor to aid in the most expeditious operation thereof.

A still further object of the present invention is to provide means and methods in accordance with any one or more of the preceding objects which operate to insure that reading or writing will not occur on a Wrong magnetic data-storage strip and, if such reading or writing is attempted, an indication of such an attempt will be made available to the data processor.

An additional object of the invention is to provide means and methods in accordance with any one or more of the preceding objects such that a command ow arrangement is provided for the data processor which permits the accurate section of one or more random access storage devices, and selected strips therein, in a manner which makes possible the most expeditious use of processor operating time, and a high degree of system exibility.

Yet another object of the present invention is to provide means and methods for establishing an operational sequence for a random access storage device of the type disclosed in the aforementioned patent application so as to achieve maximum reliability of operation.

An additional object of the present invention is to provide the means and methods of the aforementioned objects in highly reliable form, in a simple and practical manner, and with a minimum of complexity and expense:

As will be explained in considerable detail hereinafter, the above objects are accomplished, in accordance with a typical embodiment of the present invention, by providing properly located strip position-sensing means on each random access storage device, and logic and control means cooperating therewith so as to provide optimum control of each device in response to control signals generated by the data processor during random access storage unit commands; the position-sensing means and the logic'and control means also cooperate to provide status signals for each random access storage device which are made available to the processor to permit the processor to make the most expeditious use of its high speed operating capability, while also permitting maximum utilization of the random access characteristics of each storage device.

The specific nature of the present invention as well as other objects, uses, and advantages thereof will become apparent from the following description of a typical embodiment of the invention illustrated in the accompanying drawings in which:

FIG. 1 is a general block diagram of an overall system in accordance with the invention;

FIG. 1a is a perspective View vof principal portions of the random access storage device 150 in assembled form, with portions broken away and parts including a base plate removed to facilitate disclosure of certain details;

FIG. 2 is a verti-cal view of the device of FIG. 1a, partly in section and transversely through the device, with some parts removed and some portions broken away;

FIG. 3 is a partial sectional view of various portions of the device of FIG. la; specifically FIG. 3 illustrates a capstan, a strip-gate, a transducing means, and an information-storage strip in operative relationship therewith, the transducing means and capstan being moved apart somewhat to facilitate illustration;

FIG. 3a is a fragmentary view of a typical return gate In this position, the return FIG. 4 is a face view of the multiple-head electromagnetic transducing means shown in FIG. 3 with strip-contacting shields in place, but with portions broken away, showing air passages;

FIGS. 5 and 6 are a partial-section side-view, and a face View, respectively, of a typical magazine face plate and a typical strip-loading apparatus used in the device of FIG. la; various sections are removed in FIGS. 5 and 6 to facilitate disclosure;

FIG. 6a is a sectional view of a strip-guide-bar, and a strip-restraining sprag used in the strip loading apparatus of FIGS. 5 and 6;

FIG. 7 is a sectional view of the strip-loading means depicted in FIGS. 1, 5, and 6, illustrating an exemplary information-store strip in place ready for loading into a magazine, with parts removed;

FIG. 7a is a fragmentary view illustrating the action of guide bar and loading plate means in loading a strip into a magazine;

FIG. 8 is a partly-schematic partly-sectional diagram of various blower and drive portions of the device of FIG. 1; specifically, FIG. 8 illustrates principal support means, Ia strip-driving capstan, associated apparatus used to drive the capstan, and pneumatic apparatus employed to exhaust and supply air;

FIG. 9 is a partial-section View of a capstan and spider means shown in part in FIG. 8, taken on line 9 9 in the latter figure, with parts broken away;

FIG. 10 is a partial-section view depicting various other portions of the device of FIG. la; specifically FIG. 10 illustrates an air-entrance grille, a strip-selector rod, the actuating means for the rod, and the spatialrelationship of those parts to each other and to a plurality of information-store strips;

FIG. l1 is a face View depicting the driven ends of two strip-selecting rods and their respective driving or actuating means, such as may typically be employed in the selecting and releasing means 30 generally shown in the device of FIG. la;

FIG. 12 is a view showing strip suspending and strip selecting bar and rod means, with a typical information storage strip retained by the bar and rod means, such as may be employed in the selecting and releasing means 30 generally shown in the device of FIG. la;

FIG. 12a is an enlarged fragmentary view of FIG. 12 depicting details of strip-selecting and strip-suspending means in operative relationship with an information-store strip with a portion of -the latter broken away;

FIG. 13 is a view indicating the relative dispositions of the strip and the strip suspending and releasing means of FIG. 12, shortly following selection and release of a strip;

FIG. 14 is a view of a typical information-storage strip, with a par-t broken away, illustrating the means used for coding individual strips;

FIG. 15 is a binary truth table, with portions removed, indicating the coding conguration or plan for a plurality of information-store units or strips;

FIG. 16 is a schematic view of the random access storage device 150, showing the pertinent electrical means incorporated therein for actuating the various mechanical components of the device FIG. 17 is a block diagram of a typical overall system in accordance with the invention illustrating, generally, various communication lines provided between the data processor and a plurality of random access storage units;

FIG. 18 is .a more detailed block diagram showing the specific communication lines provided between the data processor and a particular random access storage unit M1 in FIG. 17;

FIG. 19 is a block diagram of the controller 250 in FIG. 18 showing the two functional components thereof and the communication lines provided therebetween;

FIG. 2O is a circuit diagram of the logic circuitry 360 shown in block form in FIG. 19;

FIG. 21 is .a circuit diagram of the information circuitry 400 shown in block form in FIG. 19;

FIG. 21a is a series of graphs illustrating typical signal waveforms in the diagrams of FIGS. and 21;

FIG. 22 is a schematic diagram illustrating a typical command llow structure for executing random .access storage unit commands in accordance with the invention;

FIGS. 23 and 24 are circuit diagarams generally illustrating typical circuitry which may be provided in the data processor for achieving branching in response to certain random access storage unit status signals;

FIGS. 25 lto 27 inclusive are timing diagrams illustrating typical overall system operation, in accordance with the invention; and

FIG. 28 is a schematic view of various modications which may be incorporated in the random access storage device 150 shown in FIG. 16 in order to `adapt it for wider applications.

Like characters and numerals designate like elements throughou-t the figures of the drawings.

INTRODUCTION Referring to FIG. 1, a general block diagram is shown of a typical overall system in accordance with the invention, including a high-speed electronic data processor 180, and a plurality of random access storage units M1 and M2 communicating therewith. As is well known, a data processor is a device which is able to accept data and to perform logical operations thereon in accordance with one or more commands (or instructions) for which the processor is programmed, the end result being, of course, to provide the desired processing of the input data.

A data processor such as illustrated at 180 in FIG. 1 may, for example, include a program control unit which governs the command ow arrangement, an arithmetic unit for operating on the data in accordance with one or more commands, an internal storage means (usually of limited capacity, such as a core memory) for the intermediate storage of data and/or permanent storage of commands `and other program data, and various registers and logical circuitry las may be required for manipulating data during processor operation. Such a data processor is generally well known in the art and is not the subject of the present invention. Consequently, in order not to distract from the present invention, further description of the data processor will be given only as is necessary to permit the novel features of this invention to be understood and put into practice using presently available knowledge.

To take advantage of the data processing capabilities of a data processor, means must, of course, be Provided so that the data processor will be able to communicate with other devices. Specifically, means must be provided for inputting and outputting data to and from the processor as may be required in any particular application. Means used for inputting and outputting data are commonly referred to as input units, output units, or inputoutput units, depending on whether the unit performs the functions of inputting, outputting or both. Typical of such units are punched card readers, printers, electric typewriters, magnetic tape units, etc. A typical computer system may then be considered as comprising the cornbination of a data processor and any input, output, and input-output units employed therewith.

As pointed out previously, the present invention is primarily concerned with improved ymeans and methods for coordinating the operation of a data processor with one or more random access storage devices of the type disclosed in the aforementioned copending patent application Serial No. 12,032. Such random access storage devices fall into the class of input-output units, and thus may be considered as a replacement for, or as a supplement to, a conventional magnetic tape unit. The important difference, however, is that in addition to providing the sequential accessing capability of a magnetic tape unit, as well as its high capacity storage capability, such an output unit also provides a fast random access capability. In FIG. l, two such random access storage units M1 `and M2 are shown communicating with the data processor 180, each of which may be considered as including (1) a basic random access storage device 150 generally corresponding to the device disclosed in the .aforementioned copending patent application Serial No. 12,032, and (2) a controller 250 (disclosed only in very general form in the aforementioned patent application) which serves to coordinate communication between the data processor 180 land the basic random access storage device 150.

Having thus generally described the overall system shown in FIG. 1, the details of a typical embodiment of the `basic random access storage device of FIG. l will now be described with particular reference to FIGS. 1a through 16, inclusive. This description will, for the most part, ybe of a mechanical nature :and will be generally similar to that provided in the aforementioned copending patent application Serial No. 12,032. Consequently, if familiarity has already been gained with this copending application, or if the mechanical details are not of present concern, it will be sufficient to merely read the General Description section immediately following this paragraph, and then to skip to FIG. 16 and the section entitled Electrical Means and Operative Description. These two sections should provide sucient background to permit a complete understanding of the remainder of the description, which is concerned with the construction and arrangement of the controller 250 and the manner in which it communicates with the processor and the basic random access storage device 150. It should be noted for purposes of comparison that the chief structural difference between the random access storage device 150 described `herein .and the similar device disclosed in the aforementioned copending patent application is in the provision and location of the positionsensing means 601' and 60j in the transducing region as will become apparent by comparing FIG. 4 in both applications.

GENERAL DESCRIPTION OF A TYPICAL BASIC RANDOM ACCESS STORAGE DEVICE (FIG. 1a)

Referring to FIG. la, a plurality of data-storage strips 10 are releasably suspended in a magazine represented generally by the ordinal 20, by strip suspension, selecting and releasing means indicated generally by ordinal 30. The magazine 20, means 30` Iand other components of the :apparatus are supported upon frame means hereinafter described. Means 30 comprise a plurality of rod-like elements, and are constructed and arranged to support a large number of strips 10 and to be operable to select and release any desired one of the strips irrespective of its position in the magazine 2.0. The strips 10 are assigned respective binary code numbers and each strip comprises means uniquely representing its number which cooperate with the rod-like elements so that the rod-like elements may be operated in correspondingly coded configurations to release desired strips at the proper times. These means on each strip representing the strip number and the mode of oper-ation thereof for selecting and dropping any specified strip will hereinafter be explained in detail.

A released strip drops gravitationally into an operating means indicated generally at 40, and into a position in which its lower end portion engages the periphery of a perforated drum or capstan 40a comprised in operating means 40. Appropriate portions or arcs of the path of the peripheral inner surface of the capstan 40a are during appropriate intervals of time pneumatically connected to suction means for provision o-f a pressure differential between the exterior and interior of the capstan 40a whereby the strip is forcibly held in Contact with and is moved by the capstan. During operation of the apparatus the capstan 40a is continuously rotated at a 

1. RANDOM ACCESS STORAGE MEANS COMPRISING: A PLURALITY OF INDIVIDUAL DATA-STORAGE ELEMENTS RETAINED IN AN ASSEMBLED GROUP FROM WHICH ANY SELECTED ONE MAY BE REMOVED REGARDLESS OF ITS POSITION IN THE GROUP FOR THE PERFORMANCE OF A TRANSDUCING OPERATION THEREON, TRANSDUCING MEANS FOR PERFORMING A TRANSDUCING OPERATION ON A REMOVED DATA-STORAGE ELEMENT, AT LEAST ONE POSITION-SENSING MEANS FOR SENSING THE POSITION OF A REMOVED ELEMENT IN SAID RANDOM ACCESS STORAGE MEANS, AND MEANS COOPERATING WITH SAID POSITION-SENSING MEANS FOR CONTROLLING THE TIME SPACING BETWEEN THE SUCCESSIVE SELECTION OF SAID DATA-STORAGE ELEMENTS SO THAT A NEWLY SELECTED ELEMENT MAY BE REMOVED WHILE A PREVIOUSLY REMOVED ELEMENT IS UNDERGOING A TRANSDUCING OPERATION. 